1. Field of the Invention
The present invention relates to a replaceable unit for use in an image forming apparatus and the image forming apparatus into which the replaceable unit is detachably attached. Particularly, the present invention relates to a replaceable unit prevented from being incorrectly attached into an image forming apparatus and the image forming apparatus into which the replaceable unit is detachably attached.
2. Description of the Related Art
As for a replaceable unit detachably attached into an image forming apparatus, arrow-shaped recesses have been heretofore provided in a front surface of the replaceable unit in order to indicate a direction of attachment of the replaceable unit into the image forming apparatus. Contrast between each arrow-shaped recess and a portion surrounding the recess is however so insufficient that it is difficult for a user to recognize the arrow shape when the installation location of the image forming apparatus is not bright. Accordingly, there is a problem that the replaceable unit may be attached into the image forming apparatus in an incorrect direction.
In order to solve the above problem, there is disclosed an example in which an identification label is put on the replaceable unit, the identification label indicating a direction of attachment of a replaceable unit (See JP-A-2001-075328).
As for an image forming apparatus into which the replaceable unit is detachably attached, there is however another problem that it is difficult to find out where to put the replaceable unit when the inside of the image forming apparatus is dark. In order to solve this problem, there is disclosed an example in which at least one of lamps used as heat sources for an exposure unit, a light irradiation unit and a fixing unit is turned on so as to illuminate the inside of the image forming apparatus when a process cartridge in the image forming apparatus is to be exchanged for a new one (See JP-A-2-184867).